Notes

* first performance.

The original reels of the Port Chester run of '71 were audibly tainted due to a cable problem. The result is a tone which hovers around 8000 Hz with an amplitude of about +20 dB above the noise floor. This translate to a very annoying pitch, especially during quiet sections, which is in the old-tv-tube or lousy-hard-disk or maybe even the-sound-you-hear-after-you-slam-your-head-against-a-concrete-wall class of 'whine'. Because this interference is 'monochromatic' it's easy to get rid of if you have the processing power and a quick FFT algorithm. I used the filter-shaping capabilities of the Sonic Foundry Noise Reduction Plugin to tailor a very narrow notch filter which attenuated the interference without affecting the rest of the signal. And it's all done in the digital domain. Huzzah!

As a side note, I actually ended up crafting many filters to process these shows. The frequency of the interference actually drifted anywhere from 7700 to 8100 Hz during a given show. This was probalby due to a slightly wandering reel speed. It made my work harder but when I tried a much wider filter I started to be able to hear the attenuation in the music. The filters generally go like this (see info file for diagram).

The end result is no more annoying whine!

I also removed some of the nasty mic feedback in the 2/18/71 Bertha using this type of filter.